Embodiments of the present invention relate to networking, and more particularly to techniques for optimizing the manner in which next-hop information associated with routing information is stored and used by a network device.
A networking environment typically comprises multiple networks. The networks may be of the same or different types and may use the same or different communication protocols for communication of data. Communication of data within the networks and also between the networks is typically facilitated by network devices such as routers, switches, etc. A network device may be connected to one or more other network devices and/or networks via one or more links or interfaces.
In a typical network environment, the number of network devices is generally far less than the number of networks that are connected by the network devices. For example, the number of network devices in a network environment may be in the order of hundreds while the number of networks is typically in the order of ten thousand, hundred thousand, etc. The number of networks in a network environment is thus typically several orders of magnitude greater than the number of network devices. Further, in a typical network environment, the number of network devices directly connected to (or neighboring) a specific network device is generally far less than the number of networks or routes in the network that are reachable via the specific network device.
As indicated above, network devices are connected to each other or to networks via links. A cost may be associated with a link signifying the cost of communicating data via that link. The cost associated with a link may be based upon various different metrics such as link bandwidth, delay, etc. The cost associated with a link while carrying data in one direction may be different from the cost associated with the same link while carrying data in the opposite direction.
In order to facilitate communication of data, a network device stores routing information that is used by the network device to determine how data received by the network device is to be forwarded to facilitate communication of the data to its intended destination. The routing information may be stored in the form of a routing table. The routing table for a network device stores information for a set of routes that are reachable from the network device via some neighboring network devices. A route in the routing table may be an address associated with a network device or a network in the network environment. The set of routes stored in a routing table for a network device thus represents a set of addresses associated with network devices or networks that are reachable from the network device. Each route in a routing table for a network device is generally associated with a next-hop entry, where the next-hop entry identifies one or more addresses of neighboring network devices to which data received by the network device is to be forwarded in order to facilitate communication of the data for the route, and for each such address, a link connected to the address and to be used for communicating data to the address.
Since the number of routes in a routing table can be very large, the size of the routing table itself can be quite large. Accordingly, a large amount of valuable memory resources have to be allocated for storing the routing and next-hop information. The increased size of the routing and next-hop information also makes it difficult and cumbersome to process.